1. Field of the Invention
Because of the high cost of lumber, the construction industry is turning more and more to the use of metal members for studs, joists, columns, and beams. Such members are generally in the form of channels, and as such require specialized fastening techniques. As is known, channels conventionally comprise an elongate web portion and two side flanges emanating from the longitudinal margins of the web portion, and from the same face of the portion. Thus, simply nailing channel members together is no longer possible nor desirable.
In some instances, such as in framing doors and windows, it is particularly desirable that two such channels be joined together back to front, with their longitudinal axes aligned, to create the rough jamb. The composite so formed is secured to a wood jamb the surface of which is finished, and also, in some cases, is secured to the gypsum board. Conventionally, the wood jamb is secured to a web of the channels, while the gypsum board is attached to the channel side flanges.
The invention concerns means for joining channels together in such a manner, whereby a composite structural member is created.
2. Description of the Prior Art
Channel members have been assembled together in a variety of configurations, by means of a variety of clips. Thus, channels have been held together at right angles to each other, by clips such as those shown in U.S. Pat. No. 3,319,983. These have not been suitable, however, to join the channels together with their axes aligned. One quite apparent reason is the absence in such clips of a portion connecting the clip to the web of one of the channels -- a necessary feature when the channels are joined back to front.
Still other channels have been joined by clips with their longitudinal axes aligned, but conventionally the junction is achieved front-to-front. Clips for such an assembly again lack the capability for connection to the web, and instead emphasize the use of tabs or notches for gripping the side flanges of the channels. Examples are shown in U.S. Pat. Nos. 2,059,565 and 2,123,458. The difficulty with this construction is that both channels are closed off, leaving the interior inaccessible, such as is necessary for the insertion of insulation. Furthermore, it is necessary that the web portion of both channels be as close as possible to the wood portion of the jamb, when used for this purpose, for maximum strength. A front-to-front construction obviously spaces one web portion too far from the other.
A recent technique has permitted the channels to be joined back-to-front. As depicted in FIG. 1, this prior construction requires the use of a wood blocking between the two channels. The disadvantage of such a technique is that it renders difficult the screw attachment of the wood jamb or the gypsum board to the composite member.